* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  transition: all 1s;
}

#app {
  display: flex;
  flex-direction: column;
  height: 45%;
  position: fixed;
  right: 0;
  left: 0;
  width: 370px;
  margin: auto;
  top: 0;
  bottom: 0;
  border-radius: 16px;
  overflow: hidden;
}

nav {
  height: 60px;
  background-color: aliceblue;
  line-height: 60px;
  display: flex;
  padding: 0 25px;
  justify-content: center;
  opacity: .6;
  position: absolute;
  right: 0;
  left: 0;
}

button {
  cursor: pointer;
  margin: 0 4px;
}

.main {
  width: 100%;
  height: 100%;
  background-color: wheat;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
}

.main>div {
  padding: 10px 15px;
  background: white;
  border-radius: 10px;
}

.btncolor {
  margin-top: 18px;
  border: 0;
  padding: 10px;
  border-radius: 10px;
}

.btncolor:hover {
  background-color: black;
  color: white;

}

div>span {
  padding: 2px 4px;
  background: #dddddd;
  border-radius: 4px;
}